1. Field of the Invention
The present invention provides a method of sealing a conduit within a well bore penetrating a subterranean formation whereby the integrity of particular regions of a subterranean formation separated by natural barriers is maintained.
2. Brief Description of the Prior Art
Liquid waste from industrial plants is being disposed of by injecting the liquid waste into subterranean formations. Subterranean formations suitable for accepting liquid waste accept large volumes of waste and are generally separated by natural barriers from formations containing potable water or useful fluids such as oil and gas.
Some of the liquid waste which is disposed of in subterranean formations is corrosive to the steel and the hydraulic cement which has historically been used in the completion of well bores penetrating subterranean formations. In one method of completing well bores penetrating subterranean formations, a steel conduit is placed in the well bore and a hydraulic cement sealing composition is placed between the conduit and the well bore to isolate the zones traversed by the well bore. An example of corrosive liquid waste being disposed of in this manner is acidic liquid waste from steel pickling baths. Certain acids can corrode steel to the point of failure and can dissolve hydraulic cement. If this happens, the liquid waste could be injected unknowingly into a zone containing potable water or other useful fluids.
Well bores through which liquid waste is injected into subterranean formations should be completed with materials which will not be corroded by flowing the liquid waste through the well bore. Epoxy resin has been found to be resistant to degradation by liquid waste containing many inorganic compounds.
To use epoxy resin for the completion of liquid waste disposal wells, the epoxy must be mixed with a curing or hardening agent which will harden the epoxy resin after a latent period such that the epoxy resin composition can be placed into specific areas in the disposal well. The epoxy resin composition should also include a liquid diluent for the epoxy resin such that the epoxy resin composition will have a viscosity low enough for placing the epoxy resin composition in the disposal well by pumping. The diluents also must be able to absorb sufficient heat to prevent intense heat build-up within the epoxy resin composition while the epoxy is being mixed with the curing agent and diluent and while the composition is being placed in the well bore. Additionally, the cured epoxy resin composition should be immune to stress cracking.
The rate of polymerization of the epoxy resin composition, preferably, should be relatively insensitive to the presence of contaminants such as quantities of water.
To maintain isolation of liquid wastes being injected into certain subterranean formations, epoxy resin compositions which remain substantially free of stress related cracks, particularly when the cured resin is subjected to fluctuations in temperatures, would be desirable. The epoxy resin also can be used to seal cracks or holes in a conduit penetrating a subterranean formation.